Impact tool for making connections



Dec. 6, 1960 K. M. HAMMELL IMPACT TOOL FOR MAKING CONNECTIONS FiledMarch 8, 1954 lag INVENTOR.

Kemper M. Humane IMPACT TooL FOR MAKING CONNECTIONS Kemper M. Hammell,Harrisburg, Pa., assignor to AMP Incorporated Filed Mar. 8, 1954, Ser.No. 414,602

1 Claim. (Cl. 29-254) The present invention relates to improvements inmethods of and tools for making an electrical connection between anelectrical terminal and a contact wherein one part provides a recesswhich receives and frictionally engages a plug portion of the otherpart.

One known type of such a connector includes a tapered plug terminal, orthe like, adapted to frictionally engage a receptacle contact member,usually with one or the other of said members in fixed position. Thistype of connection is advantageous, particularly where many lead wiresare to be attached in a small area. However, there remains a risk thatoperators may make such connections carelessly so that the connectionmay be less than perfect even where the connector parts are properlydesigned and accurately made.

An object of the present invention has been to provide an implement ortool for connecting these parts in a manner to insure optimum mechanicaland electrical engagement between them without injury to or impairmentof either.

A further object has been to provide a tool by which one part, as aterminal attached to wire end, may while held by the tool be teleseopedand frictionally engaged with a receptacle contact member quickly andsecurely in a simple operation even where the available working space islimited and the parts are not otherwise readily accessible.

It is also an object of the invention to provide an attaching toolaffording substantially uniform optimum frictional connections for anygiven type or size of terminal, in part by automatic control of themaximum locating force applied to the part by a given type of tool, andin part by predetermining the energy applied to drive home the terminalafter locating it by controlled force.

A further object of the invention has been to provide a method and atool whereby, in operation, a tell-tale marking, or the like, is left onone of the parts automatically, thus indicating that they have beenjoined under optimum conditions for producing an effective and durableconnection.

In the method according to the present invention of effectinginterengagement of connector parts, one of said connector parts isfitted into an appropriate tool and the tool pressed axially to giveinitial telescoping engagement of said parts; and advantageously, theparts are driven into final frictional engagement, with high radialpressure, by an impact of predetermined magnitude. During the initialinserting operation the tool advantageously cushions the appliedpressure and applies a driving force having the requisite direction andmagnitude to bring the connector parts into mating relation; andadvantageously when a predetermined force for initial insertion has beenreached, the tool automatically applies the predetermined energy todrive the parts into final contact relation and, if desired, leaves amark on one of them.

A convenient form of hand tool according to the present inventionincludes a handle and a shank (somewhat like an ordinary screw driver)the end of the shank being formed to receive and engage a terminalconnector for axial push and to accommodate a wire extending from theback end of the terminal. For more precise insertion, my inventionprovides a tool comprising a spring-pressed plunger and a hammer mountedfor longitudinal movement in a holder, said plunger having aterminal-engaging socket or groove at its outer end for accommodating aWire attached to the terminal, and means for engaging a spring throughwhich it engages with said holder and is pressed by said holder intoinitial engagement with the terminal, and a hammer actuating spring is:compressed or loaded to a predetermined extent by initial inwardmovement of the plunger and the hammer is then released to deliver adriving blow through said plunger to the part initially engagedtherewith. Where the driving face of the plunger carries an appropriatedie or dies, this blow also leaves a mark on the connector.

Other objects and important features of the invention to which referencehas not been made hereinabove will appear in the following descriptionand claims.

Although in the accompanying drawings I have shown a preferredembodiment of a tool according to my in-. vention and have described thesame and modifications thereof and of the method according to myinvention in this specification, it is to be understood that these arenot intended to be either exhaustive or limiting of the invention, buton the contrary, are chosen for the purposes of illustrating theinvention in order that others skilled in the art may fully understandthe invention, its principles and the application thereof, and that theymay embody it and adapt it in numerous forms, each as may be best suitedto the requirements of its particular use.

Figure l of the appended drawings is a central longitudinal sectionalview of a plunger, hammer and spring assembly in a holder with the outerend of the plunger broken away;

Figure 2 is a view in perspective on enlarged scale of the socket orgrooved end portion of the plunger;

Figure 3 is an outer end elevation of the socket portion of the plungershown in Figure 2;

Figure 4 is a fragmentary bottom plan view of the socket portion of theplunger shown in Figure 2;

Figure 5 is a fragmentary top plan view with the socket portion of theplunger shown as about to engage the shoulder of a receptacle typeterminal; and

Figure 6 is a view similar to Figure 5 of the socket portion about toengage the shoulder of a plug type terminal.

Although, as suggested above, the invention may be embodied in a simplescrew-driver-like tool, e.g., by rigidly securing a suitable head on ashank or hand grip, the present invention is advantageously embodied ina hand tool which utilizes the operating mechanism, as in Figure 1, of acommercially available self-triggering nail set or center punch-but withthe outer end of the operating plunger specially designed andconstructed as shown in Figures 2, 3 and 4 and hereinafter described.For more accurate control over the inserting force, e.g. for a taper pinconnector, or receptacle, the terminal-engaging plunger of the tool mayadvantageously push against a spring-driven hammer to load its spring toa predetermined extent, whereupon the hammer is released to be actuatedby the loaded spring and impact against another part of the plunger.

As shown in Figure 2, a tool according to the present invention includesa shank 1 which provides a terminalengaging socket or groove 2 open atits outer end. The outer end of groove 2 presents a flared openingdefined in part by inclined driving faces 3 each of which has a markingdie 4 extending beyond its surface. Groove 2 is advantageously formed atits upper end with a rounded tapering surface 5 providing a guide wayfor a wire 6 to Patented Dec. 6, 1960 which is attached a terminal, as7, Figure 5, or 8, Fig ure 6.

When used for connecting a terminal and a receptacle, the terminal ispositioned with its insulation engaging portion engaged in groove 2 andwith its shoulder portion 11, 11a between driving faces 3 and dies 4.The wire 6 extends thence into and along groove 2.

When the tenninal and its wire are thus engaged in groove 2, the outerend of the terminal is engaged with a contact, as plug 12 or receptacle12a, which are telescoped together with the necessary force applied bymanual pressure on the tool handle, or by impact, or both.

Such a tool with a rigidly connected handle or holder and with agrooveas described, enables a careful skilled operator to make consistentlyperfect connections. In ordinary manufacturing, however, less skilledand less careful operators must be employed for such work. A furtherimprovement. of my invention assures proper connection even with suchoperators. To this end the grooved end. portion of shank 1 abovedescribed and shown in Figure 2 is conveniently incorporated in ormounted on a plunger 13, Figure 1.

A holder 14 for plunger 13, as shown, is made in three sections threadedtogether and has a central longitudinal bore accommodating at its openend the plunger 13 pushed toward its grooved end by a spring 15. Ahammer 16 is slidably mounted in the opposite closed end of said boreandis pushed toward the plunger 13 by a spring 17. A plug 18 screwed intothe bore in the lower part of holder 14 serves as an abutment for springand has acentral opening 19 serving as a bearing to hold plunger 13toits axial position during sliding movement.

The middle section of the holder 14' between said lower section and theclosed end section, has a bore which decreases in diameter toward theupper end so that an annular, sloping cam surface 20 is formed therein.The hammer 16 is of a diameter slightly less than the narrower portionof the bore so that it may slide freely therein. An annular flange 16aat the lower end of said hammer has a free sliding fit in the lower orlarger portion ofsaid bore, the lower end of the hammer having a centralhole 16b.

, Hammer 16 also has a transverse recess 21 (Figure 1) which receives aslidable detent 22 provided with an axial hole 23 slid'ably fitted tothe upper shaft of plunger 13. A flat spring 24, secured to one side ofhammer 16 in recess 25, is arranged with its free end extending intorecess 21 and bearing against one side of detent 22 which is thus pushedtoward the opposite side of the bore in holder 14 as shown in Figure 1.The other end of de tent 22 is rounded and extends radially beyond theopening of recess 21 to ride on the inner surface of said bore in holder14.

The inner end of plunger 13 extends through the hole 165 in hammer part16 and may have an end projection 26 of reduced diameter extendingbeyond a shoulder 27 which normally engages the detent 22 while saidprojection 26 extends into hole 23 of said detent.

In operation, when pressure is applied to holder 14 in the direction ofthe arrow (Figure 1) and a wire with a terminal thereon is engaged inthe socket (as seen in Figure 6, for example) terminal 8 freely enterscontact receptacle 1211. When, with further inward movement of. terminal8', the frictional contact between said parts increasessufficiently,plunger, 13 is moved inwardly compressing spring 17, the inner end ofsaid plunger being pressed against detent 22 which moves hammer 16upward against said spring 17. When this movement of hammer 16 bringsthe rounded end of detent 22 against shoulder. 20, said detent is movedtransversely against resistance of spring 24 until'its hole 23 is linedup with plunger 13; and thus it is dislodged from shoulder 27.

. The hammer when thus released is driven downward by spring 17 todeliver a sharp blow when the upper end of plunger 13 strikes the innerend of the bore 16b in the hammer. The energy of this impact ispredetermined by the characteristics of spring 17 and the depth of holes23 and 16b. The force exerted for initial seating of the terminal beforethe impact occurs is predetermined by the location of cam shoulder 20and the characteristics of spring 17 (i.e., the loading of the spring atthe point where the hammer is triggered for impact). When impact occurs,the operator knows that the inserting operation is complete. The mass ofhammer 16 and the power factor to be supplied by springs 15 and 17 willbe designed for optimum degree of insertion for a given type and sizerange of terminals and contracts to be connected. This device isparticularly advantageous with terminals and receptacles of the generalkind disclosed in the application Serial No. 400,996, filed December 29,1953.

Where marking of the connector part is involved, the character of thedies 4 will be such as to, leavea sensible mark on the material of thestruck part by a blow which effects optimum connection between theparts;

From the foregoing it is apparent that the terminal connecting andmarking tools described above are well suited to attain the ends andobjects herein directly and indirectly set forth; that they can bemanufactured by conventional techniques; and that the various featuresand arrangements of parts can be modified readily so as best to suit aparticular use. Certain features of the dis closure may be used toadvantage in particular applications without a corresponding use ofother features, and the disclosure may be used to advantage inparticular applications without a corresponding use of other features,and the elimination or modification of such features is to be construedas within the scope of this invention unless specifically excluded bythe following claim or required by the scope of the prior art;

I claim:

For use in installing a connected lead wire and tapered connector havinglateral driving abutments intermediate its length in mechanically-wedgedelectrical connection with a mating connector part, a tool including aplunger mounted to slide endwis'e inwardly in a recessed handleinitially to load a spring enclosed therein and means for impact drivingsaid plunger in the opposite direction when said spring is released fromloaded condition after predetermined inward movement of said plunger,the outer part of said plunger relative to said handle providing anaxially extending shank having an axially disposed longitudinalconnector-engaging groove therein, said groove at one end openingthrough the end of said shank to define divergent driving faces at theend surfaces of the groove sidewalls adapted to drivingly engage saidabutments, and a guideway at the other end of the groove adapted forengaging a connected portion of the lead wire of the connector wherebythe connector and adjacent lead wire portions are maintained in axialalignment along said shank in position for installation with the lateraldriving parts abutted against said driving faces.

References Cited in the file of this patent UNITED STATES PATENTS1,444,231 Berge Feb. 6, 1 923 1,720,318 Chisholm July 9, 1929 1,882,689Abertson Oct. 18, 1932 1,903,548 Kreis Apr. 11, 1933 1,958,329 Beard May8, 1934 2,462,774 Pollock Feb. 22, 1949 2,509,932 Leeth a May 30, 19502,521,186 Pennella Sept. 5, 1950 2,635,328 Larmour Aug. 21, 19532,686,963 Freyssinet Aug. 24, 1954 2,774,133 Sitz Dec. 18, 1956

